Micro-electro-mechanical actuator for positioning a device such as a read/write head in a disk drive

Abstract

A micro-electro-mechanical device formed by a body of semiconductor material having a thickness and defining a mobile part and a fixed part. The mobile part is formed by a mobile platform, supporting arms extending from the mobile platform to the fixed part, and by mobile electrodes fixed to the mobile platform. The fixed part has fixed electrodes facing the mobile electrodes, a first biasing region fixed to the fixed electrodes, a second biasing region fixed to the supporting arms, and an insulation region of insulating material extending through the entire thickness of the body. The insulation region insulates electrically at least one between the first and the second biasing regions from the rest of the fixed part.

1. A micro-electro-mechanical device, characterized by a body having a thickness and defining a mobile part and a fixed part,
 said body formed from a single layer of semiconductor material extending through the entire thickness of said body; 
 said mobile part comprising a mobile platform, supporting arms extending from said mobile platform to said fixed part, and mobile electrodes fixed to said mobile platform; 
 said fixed part comprising fixed electrodes facing said mobile electrodes, a first biasing portion fixed to said fixed electrodes, a second biasing portion fixed to said supporting arms, and an insulation region of insulating material extending through the entire thickness of said body, 
 wherein said insulation region electrically insulates at least one of said first and second biasing portions from the rest of said fixed part. 
 
   
   
     2. The device according to  claim 1 , wherein said fixed electrodes extend from said first biasing portion, and said supporting arms extend as a continuation of said second biasing portion. 
   
   
     3. The device according to  claim 1 , wherein at least one through trench extends through the entire thickness of said body between said mobile part and said fixed part, and said at least one of said first and second biasing portions is further delimited by said through trench. 
   
   
     4. The device according to  claim 1 , wherein contact pads are formed above said mobile platform, and electrical-connection lines extend from said pads on said supporting arms. 
   
   
     5. The device according to  claim 1 , constituting a micro-actuator for hard-disk drives. 
   
   
     6. The device according to  claim 3 , wherein said insulation region surrounds said second biasing portion. 
   
   
     7. The device according to  claim 1 , wherein said body is of monocrystalline silicon. 
   
   
     8. A micro-electro-mechanical device, characterized by a body of semiconductor material having a thickness and defining a mobile part and a fixed part,
 said mobile part comprising a mobile platform, supporting arms extending from said mobile platform to said fixed part, and mobile electrodes fixed to said mobile platform; 
 said fixed part comprising fixed electrodes facing said mobile electrodes, a first biasing portion fixed to said fixed electrodes, a second biasing portion fixed to said supporting arms, and an insulation region of insulating material extending through the entire thickness of said body, 
 wherein said insulation region electrically insulates at least one of said first and second biasing portions from the rest of said fixed part, 
 wherein at least one through trench extends through the entire thickness of said body between said mobile part and said fixed part, and said at least one of said first and second biasing portions is further delimited by said through trench, and 
 wherein said insulation region has an arched shape with ends terminating on said through trench. 
 
   
   
     9. A micro-electro-mechanical device, characterized by a body having a thickness and defining a mobile part and a fixed part,
 said body formed from a single layer of semiconductor material extending through the entire thickness of said body; 
 said mobile part comprising a mobile platform, supporting arms extending from said mobile platform to said fixed part, and mobile electrodes fixed to said mobile platform; 
 said fixed part comprising fixed electrodes facing said mobile electrodes, a first biasing portion fixed to said fixed electrodes, a second biasing portion fixed to said supporting arms, and an insulation region of insulating material extending through the entire thickness of said body, 
 wherein said insulation region electrically insulates at least one of said first and second biasing portions from the rest of said fixed part, 
 wherein at least one through trench extends through the entire thickness of said body between said mobile part and said fixed part, and said at least one of said first and second biasing portions is further delimited by said through trench, and 
 wherein said insulating region comprises at least one first and one second insulating portion and a connecting portion, said connecting portion extends laterally with respect to said through trench between said insulating portions. 
 
   
   
     10. A micro-electro-mechanical device, comprising:
 a moveable portion comprising,
 a moveable platform, and 
 a moveable electrode attached to the moveable platform; 
 
 a fixed portion having a fixed position relative to the moveable portion and formed from a single layer of semiconductor material extending through an entire thickness of the fixed portion, the fixed portion comprising,
 a first biasing portion, 
 a fixed electrode attached to the first biasing portion and facing the moveable electrode, 
 a second biasing portion, and 
 a region of insulating material extending through the entire thickness of the fixed portion to electrically insulate the first biasing portion from the second biasing portion; and 
 
 support arms that attach the moveable portion to the fixed portion. 
 
   
   
     11. The device of  claim 10 , further comprising:
 multiple moveable electrodes attached to the moveable platform; and 
 multiple fixed electrodes attached to the first biasing portion. 
 
   
   
     12. The device of  claim 10 , further comprising;
 multiple first biasing portions; and 
 multiple fixed electrodes attached to each biasing portion. 
 
   
   
     13. The device of  claim 10  wherein:
 the moveable platform is substantially circular, and 
 the moveable electrodes extend radially. 
 
   
   
     14. A disk drive, comprising:
 a disk operable to store data; and 
 a read/write head assembly comprising, 
 a micro-electro-mechanical device, comprising:
 a moveable portion comprising,
 a moveable platform, and 
 a moveable electrode attached to the moveable platform; 
 
 a fixed portion having a fixed position relative to the moveable portion and formed from a single layer of semiconductor material extending through an entire thickness of the fixed portion, the fixed portion comprising,
 a first biasing portion, 
 a fixed electrode attached to the first biasing portion and facing the moveable electrode, 
 a second biasing portion, and 
 a region of insulating material extending through the entire thickness of the fixed portion to electrically insulate the first biasing portion from the second biasing portion; and 
 
 support arms that attach the moveable portion to the fixed portion; and a read/write head attached to the moveabie platform. 
 
 
   
   
     15. An electronic system, comprising:
 a disk drive, comprising, 
 a disk operable to store data, and 
 a micro-electro-mechanical device, comprising:
 a moveable portion comprising,
 a moveable platform, and 
 a moveable electrode attached to the moveable platform; 
 
 a fixed portion having a fixed position relative to the moveable portion and formed from a single layer of semiconductor material extending through an entire thickness of the fixed portion, the fixed portion comprising,
 a first biasing portion, 
 a fixed electrode attached to the first biasing portion and facing the moveable electrode, 
 a second biasing portion, and 
 a region of insulating material extending through the entire thickness of the fixed portion to electrically insulate the first biasing portion from the second biasing portion; and 
 
 support arms that attach the moveable portion to the fixed portion.